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FTFC'18 WWII Kalinin K-12

FoamyDM

Building Fool-Flying Noob
#61
Nice

The squids did good work, but not soon enough though because my motors are acting all twitchy all of a sudden... rrrg. But I have it working right - according to the bars. looks like more solder work tomorrow.
 

FoamyDM

Building Fool-Flying Noob
#62
Progress and Trepidation

After looking through the Lippisch P13a by dr. Looping Looie thread I noticed he used a paper copy to test CG. I thought, "Great Idea!" so I printed the K-12 out on A4 paper, and started cut and folding, here's the result.
Paper Glider for CG.JPG

I tested it in the office, testing it in the hallway. Sadly it had a tendency to roll and float upside down. I had only a few "Meh" glides, then added the wing tip rudders, and adjusted... it didn't seem to have much yaw effect at that size I didn't expect much. Then added Aileron Flaps and adjusted, but still wasn't able to stop it from flopping over.

I was able to learn the CG was narrowed down it's location to 1/8" to 3/8" just in front of the back vertical leg of the spar box.

It's funny how this is Exactly where the Bomb Bay is. :)

But I couldn't manage a consistent glide. It nearly always flopped over, and or spun under. That was pretty cool.

OK I think I have 2 bad 12A escs and 1 bad 20A escs. They'd power up and go through the beep cycle but throttle up yields twitching. So I spent last night testing, re-flowing., re-soldering etc. Still bad (maybe). So while the solder joints are definitely good, I decided to pull out the un-opened 12A escs from a quad, where I replaced the stock 12A's with 20A Aikons. Soldered up the Bullets, and XT60, shrink wrap and the test on both are solid. I also pulled out a 30 Cheap ESC for the 2812 center motor for the flying Sub. Although I think I might switch up to the C-pack motor as I can set it up with a shaft in front and one in back. lending for perfect motor for propeller or water screw drive from the same source.

I have a little Time. I will have the water screw shaft in for show. For the air flights. wither way is good for air-worthiness testing.
 

Hai-Lee

Old and Bold RC PILOT
Mentor
#63
As for you inability to obtain a consistent glide from the paper mock-up I would say that it is to be expected!

The drag of the plane is far higher than the forward thrust you would ever get from the weight of the craft working through the wing shape.

What is happening is that because it has such a large cross section and so little weight the drag quickly slows the model to below stall for the wings and then the little weight the model has uses its inherent centre of mass and rolls the plane to put the centre of mass below the lift, centres for stability. The wings are now acting as parachutes,

The spinning inverted is caused most likely by differences in the parachute like lift from the wings and their aerofoil shape.

If the paper model can support an increase in weight add some for better glide response or angle the launch in a slightly nose downwards attitude and try to keep the models speed above stall.

Just a few thoughts,

Have fun!
 

FoamyDM

Building Fool-Flying Noob
#65
At this point I'm just being a scaredy pants.
logo-large-scaredy-pants1.png
Sort of..

As it stands, The elevator movement is VERY small. I need to take the 2 seconds to install the guide zip ties, which should improve the throw. Right now the motors I need are in the LPL Flying Sub, and I want one more solid stab at flight for tat bird. Before switching them over to try this out.

I also had my life upend at the end of October, still working that out too. daylight savings... I know, excuses.
 

FoamyDM

Building Fool-Flying Noob
#66
Lost motivation at the end of last year and never fixed the low throw elevators. so I didn't maiden this before the year's end. I might have it ready for a run this weekend. I'll have to see.

This still has been a truly fun challenge.